Liquid crystal display devices are mainly classified into transmission type and reflection type. The former displays with light from a backlight, and therefore its light source is stable but the consumption of energy is large; the latter displays with ambient light, and therefore its consumption of energy is low, but the display effect relies on external environment. In order to combine advantages of both display modes, a transflecting liquid crystal display device has been proposed, that is, each pixel includes both a transmission region and a reflection region.
For a transflecting liquid crystal display device, it is obvious that light in the transmission region can pass the liquid crystal layer once only, while light in the reflection region passes the liquid crystal layer twice, in which case a special solution is necessary to achieve the same display effect in both regions. The existing solutions are mainly classified into two types: dual-cell-thickness and single-cell-thickness. Dual-cell-thickness means different thicknesses of liquid crystal layer are provided in the two regions, which facilitates achieving the same display effect, but suffers from problems such as liquid crystal disorder in the transition location between two regions and difficult control over the cell gaps.
Therefore, a single-cell-thickness liquid crystal display device in which liquid crystal layer thickness is the same in both the transmission and reflection regions has a more promising development. In order to achieve the same display effect in case of single-cell-thickness, it is necessary to adjust the structure of the reflection region. For example, it is possible to have the initial alignment direction of nematic liquid crystal in reflection regions to form an angle of about 10 degree with the electrodes in a partial IPS mode (In Plane Switching) and ADS switch mode (Advanced Super Dimension Switch) liquid crystal display device. However, this would cause dark state light leakage, reduced contrast and blur boundary between two regions. In order to address the above problem, it is also possible to add an additional ¼ wave plate (in-cell retarder) in the reflection region. However, this will result in a complex manufacturing process.